In the field of semiconductor components, conventional transistors typically have an active portion that is completely surrounded by a control electrode for turning the transistor on or off depending on its state of bias. These transistors are often termed GAA (gate-all-around) transistors.
Conventional transistors may include parallel nanofingers resting on a substrate and almost completely surrounded by a control conductor. The drawback to such transistors is that the channel region rests at least completely on a substrate and is therefore not surrounded by the gate electrode.
Conventional MOS transistors with a channel completely surrounded by a gate electrode may, for example, be obtained by what is called the SON (silicon-on-nothing) process. Here, it is necessary to provide a step in which the subjacent layer of the active semiconductor portion is removed. Such a step, or underetching, entails various drawbacks because of the inevitably limited selectivity between the semiconductor intended to form the active zone and the subjacent material, commonly silicon on silicon/germanium. In particular, the channel width of the transistor is limited.
There is therefore a need for improved transistors with fingers exhibiting improved isolation characteristics and a fabrication process to make the same.